It is desirable to have a dentifrice dispensing toothbrush which uses a refillable cartridge for pumping dentifrice material to the top of a brush head. The refillable cartridge must be reusable without the need to clean after empty for repeated filling from a toothpaste tube. The steps of mounting of a refillable cartridge to a toothpaste tube and filling with the dentifrice material must be easy to perform for a person of average dexterity. The cartridge design must minimize air entrapment during filling with dentifrice material and be adaptive to different size openings of toothpaste tubes.
1. Field of the Invention
The present invention relates to a dentifrice dispensing toothbrush which pumps dentifrice material from a refillable cartridge to the brush head. In particular, the invention provides adaptive features for a refillable cartridge for mounting to small and large size openings of a variety of toothpaste tubes as well as means for minimizing and expelling entrapped air during filling of the cartridge from a toothpaste tube.
2. Description of Prior Art
In the designs of a toothpaste dispensing toothbrush as described in many patents, no design has been directed toward minimizing air entrapment during filling of a cartridge which is mounted on a toothpaste tube. For a vacuum-type pumping mechanism for a pasty dentifrice material, the presence of air pockets (or voids) in the dentifrice material reduces the pumping efficiency and can cause eventual pumping failure, which is a breakdown of the continuity of the flow of dentifrice material to the top of the brush head despite repeated pumping actions.
In filling a toothpaste cartridge from a toothpaste tube, a major source of air entrapment comes from air pockets formed at the junction of the toothpaste tube and the cartridge mounted to the tube. Also, air pockets may have existed originally inside the toothpaste tube. These air pockets must be vented out as much as possible during the filling process of the cartridge.
There has been no prior art that specifically addresses the venting of entrapped air in the filling of a toothpaste cartridge from a toothpaste tube. Many toothpaste pump dispensers are designed for one time use only and are not refillable. As typified by U.S. Pat. No. 4,301,948 by Czech et al. once a toothpaste pump dispenser is spent, the piston or follower disc reaches the end of the reservoir and blocks the entrance to the pump chamber. Since the piston is not retractable, the reservoir cannot be refilled from the bottom opening end to make a flow path to the pump chamber. Furthermore, it cannot be refilled from the spout of the pump dispenser because the flow is blocked by its one-way check valve which prevents dentifrice material from entering the reservoir.
The type of replaceable cartridge as described in U.S. Pat. No. 4,068,974 by Meyer et al. is mainly for storing liquid dentifrice and is not refillable. It does not have a follower disc required for packing the dentifrice material for vacuum pumping and it has only one opening that does not allow for venting of air inside. The Canadian Patent No. 523,340 by Vincent et al. describes a disposable toothbrush having a follower disc inside its handle for vacuum pumping of dentifrice material. The construction of the handle, which can be made separable, does not allow for venting of air during refilling and does not address the mountability to different sizes of toothpaste tube openings. In addition, the kind of replaceable toothpaste cartridge that uses a thread-type follower disc is not suitable for refilling because its follower disc cannot be pushed backward by the flow of the toothpaste during the refilling process. U.S. Pat. No. 4,384,645 describes a small size refillable toothpaste tube for conveniently storing inside a toothbrush handle for compactness; it is not for the convenience of vacuum pumping the toothpaste directly to the brush head through an internal flow channel.
U.S. Pat. Nos. 4,787,765 and 5,062,728 by Kuo describe replaceable toothpaste cartridges for vacuum pumping. Although these patents address the venting of air during insertion of a filled cartridge into the handle of a dentifrice dispensing toothbrush through holes located near the interface of the pumping chamber and the cartridge, the described venting mechanism is not applicable for the venting of entrapped air during filling of a toothpaste cartridge. Moreover, these cartridges use one-way follower discs which cannot be moved backward or removed as required for a refilling process. The kind of replaceable toothpaste cartridge disclosed in U.S. Pat. No. 5,346,324 by Kuo uses a two-way follower disc, but it does not have features for venting entrapped air during refilling and for adaptive mounting of the cartridge to different sizes of toothpaste openings.
Another desirable feature of a refillable cartridge is the use of a two-way follower disc having different friction forces in its forward and backward movements inside a cartridge tube. While maintaining the sealing capability, the friction force of the follower disc against the tube wall should be as low as possible for pumping a wide variety of dentifrice materials including those of low cohesive strength. On the other hand, sufficient friction is needed to support the weight of the dentifrice material in a filled cartridge without slipping off in a free standing position. These opposite frictional requirements as described above have not been addressed in the prior art of toothpaste dispenser designs such as in U.S. Pat. No. 4,651,904 by Schuckmann and U.S. Pat. No. 4,903,867 by Mettenbrink et al..
It is therefore an object of this invention to provide adaptive mounting features for a refillable toothpaste cartridge used on a toothpaste dispensing toothbrush to provide a snug-fit to different sizes of toothpaste tubes for filling the cartridge. It is also an object of this invention to provide design features for a refillable cartridge for venting entrapped air during the filling of the cartridge and for higher pumping efficiency. It is a further object of this invention to provide a venting flip-cap having special features for venting entrapped air in the junction area of a toothpaste tube mounted with a refillable cartridge.